A sensing platform of molecular imprinted polymer-based polyaniline/carbon paste electrodes for simultaneous potentiometric determination of alfuzosin and solifenacin in binary co-formulation and spiked plasma

Abstract

Solid contact ion-selective electrodes (ISEs) have witnessed versatile applications in pharmaceutical and biological analysis however they suffer from some limitations. Besides formation of water layer, the doped ion exchanger in sensing membrane fails to distinguish between two ionic species having relatively similar lipophilicity and carrying same charges. Those shortcomings practically hampered the simultaneous determination of alfuzosin and solifenacin in their combined pharmaceutical combination. Hence, this paper was directed to develop two carbon paste electrodes allowing their simultaneous determination based on molecular imprinted polymers (MIPs). Efforts were firstly directed to stabilize the potential signals through synthesis of polyaniline (PANI) nanoparticles with 26 nm particle size as confirmed by means of UV-spectrophotometry, Zeta-sizer and transmission electron microscope. This was followed by its doping at electrode/ion selective membrane interface leading to diminished potential drift, better Nernstian slopes and lower limit of detections. Secondly, MIPs for each drug were prepared by precipitation polymerization technique and fully characterized by Fourier-transform infrared spectroscopy, field-emission scanning electron microscope, differential scanning calorimetry, surface area analysis and rebinding studies. The prepared MIPs were then incorporated in membrane cocktail and doped over PANI layer. The graved cavities inside MIPs act as synthetic host-tailored receptors that could recognize and bind specifically to each drug. The obtained Nernstian slopes were 57.16 mV/decade for alfuzosin MIP-based sensor and 58.17 mV/decade for solifenacin MIP-based one with respective LOD values of 7.9 × 10−7 M and 8.9 × 10−8 M. Moreover, no interference was ostensibly detected from dosage form excipients, plasma constituents or degradation products/official impurities allowing quantification of alfuzosin and solifenacin in their combined capsule, spiked human plasma and in presence of their degradation products.